EP Patent Application Publication No. 2 221 608 discloses a test method and test device for analyzing a body fluid by means of analytical test fields stored on a test tape. To ensure an increased security against operating and measuring errors, a control value is determined from a time-dependent and/or wavelength-dependent change of the measurement signals. The measurement signals then are processed as valid or discarded as erroneous depending on a preset threshold value of the control value. This document further discloses that high air humidity, as well as exposure to UV radiation, may lead to a signal change similar to sample application, and thus result in a start of the measurement. In this context, it is proposed that body fluid/liquid sample application is detected when a signal change is above a predetermined threshold value (e.g., of about 5%), and a fault is detected when it is below this value if necessary after a specified waiting time. In the latter case, the test field is discarded, and the measurement must be repeated.
For the foregoing reasons, there is a need for improved methods of determining/detecting body fluid sample application to test elements to provide reliable results and to avoid a loss of test elements even under unfavorable ambient measurement conditions.